1. Field of the Invention
The present invention relates to the removal of heparin from blood plasma test samples.
2. Description of the Prior Art
Heparin is widely used as a parenteral anticoagulant for the treatment of thromboembolic patients, for the prophylactic treatment of high risk embolic patients and to reduce the incidence of deep-vein thrombosis after major surgery. Thromboembolic conditions are characteristic of disease states such as coronary thrombosis, venous thrombosis, pulmonary embolism and the like. During treatment, it is necessary to determine the patient's clotting time in the absence of heparin, i.e., the true blood plasma clotting time. Thus, it is necessary to neutralize or remove the heparin from the sample of the patient's blood plasma prior to coagulation testing.
Conventionally, heparin is neutralized by reaction with protamine, as described by Allen, J. G., et al., "A Protamine Titration as an Indication of a Clotting Defect in Certain Hemorrhagic States", in J. Lab. Clin. Med. 34:473-476 (1949); and by Perkins, H. A., "Neutralization of Heparin In Vitro with Protamine; A Simple Method of Estimating the Required Dose", J. Lab. Clin. Med. 48:223-226 (August, 1956). Polybrene, a synthetic polymerized quaternary ammonium salt, has also been used to neutralize heparin (see Godal, H. C., "A Comparison of Two Heparin Neutralizing Agents: Protamine and Polybrene", Scandinav. J. Clin. & Lab. Invest. 12:466-457, (1960).
While the above-mentioned procedures have been used successfully, a tedious titration is required since protamine and polybrene are soluble in plasma. Any excess not combined with heparin will remain in the plasma, frequently undetected, and interfere with the coagulation test. Thus, the accuracy of the coaguation test itself is questionable.
The reaction of glutaraldehyde with various proteins to give soluble and insoluble products has been reported by A. Habeeb, et al. in Arch. Biochem. Biophys. 126:10-26 (1968); and by E. Jansen, et al. in Arch. Biochem. Biophys. 144:394-400 (1971). Neither of these studies discloses the reaction of glutaraldehyde with protamine.
In view of the deficiences of the conventional art methods, there is a need for a simple, rapid procedure for removal of heparin from blood plasma samples without adversely affecting subsequent coagulation testing of the plasma samples.
Co-pending application Ser. No. 931,031 filed Aug. 4, 1978 (2100.1267) by James E. Turner, James R. Butler and Arthur L. Babson, entitled REMOVAL OF HEPARIN FROM BLOOD PLASMA SAMPLES USING TRIETHYLAMINOETHYL CELLULOSE describes a method for removing heparin using fibrous triethylaminoethyl cellulose; and co-pending application Ser. No. 931,032 filed Aug. 4, 1978 (2100.1362) by James E. Turner, James R. Butler and Frank W. Goodhart, entitled REMOVAL OF HEPARIN FROM HEPARIN-CONTAINING BLOOD PLASMA SAMPLES USING A TRIETHYLAMINOETHYL CELLULOSE TABLET, describes a microcrystalline cellulose/triethylaminoethyl cellulose table suitable for removing heparin from blood plasma samples.